Bbtts. — Autecology of Plants of PeridotiU Belt, Nelson, 



239 



The spongy tissue consists of fairly large roundish cells which have very 

 thin walls and which contain only a few small chloroplasts. There are fair- 

 sized air-spaces between the cells of the spongy tissue, which forms a water- 

 storage tissue. A few of the cells of the chlorenchyma contain crystal 

 aggregates of calcium oxalate. 



The vascular bundles are small, and have only a small amount of lignified 

 tissue. Each bundle is surrounded by a sheath of parenchymatous cells, 

 which contain a few small chloroplasts. 



Stem (fig. 10). — The epidermis is composed of more or less rounded cells 

 with thick cell-walls. A ridged cuticle is also present. Inside this layer 

 there is a zone of tissue 5 or 6 cells deep ; these cells are empty, have 

 thickened walls, and near the outside are regular in shape, but towards the 

 inside are more irregular. The innermost cells of this tissue are suberized. 



Fig. 9. — Colobantkus quite nsij. Transverse section of half of leaf (x 125). a, thick 



cuticle ; b, small raised stoma ; c, aqueous tissue. 

 Fig. 10. — Colobantkus quitensis. Transverse section of stem ( X 125). a, epidermis ; 



b, dead cortex ; c, suberized tissue ; d, thick-walled cortex ; e, phloem ; 



/, xylem. 



Next comes a band of small suberized cells. The 2 innermost layers 

 of these cork cells are practically square, but the remainder of this band is 

 composed of the usual flattened cork cells. All the cells of this tissue have 

 thin walls. 



The cortex consists of small cells with very thick mucilaginous cell-walls 

 and small cavities. 



The phloem forms a continuous wide band around the xylem ; the cell- 

 walls are thickened and mucilaginous. The xylem consists of vessels of 

 fairly large diameter, together with a large amount of xylem parenchyma. 



The pith is small and solid, and consists of rounded or polygonal cells 

 which are closely packed together, so that there are only minute air-spaces 

 between the cells. 



7. Clematis Colensoi Hook. f. var. rutaefolia Hook. f. (?). 

 Growth-form. — A woody liane with slender flexuous branches. The 

 stems and branches are glabrous, but silky at the tips. The leaves are 

 biternate, with the secondary leaflets stalked. The leaves are slightly 

 coriaceous. 



